The present invention relates to treatments for reducing the post perm odor in hair after the permanent wave operation. Post perm odors have been found to exist due to the use of hair reducing agents such Thioglycolic Acid, Thiolactic Acid, GTG, Cysteine, Cysteamine, Bisulfite or other product compounds that are entrapped into the porous structure of hair. The higher the porosity of hair the higher the binding affinity of the chemical compounds with hair or the higher the level of the odoriferous residues. Other factors that affect the binding affinity are molecular size, net change of reducing agent, electro-static charge of hair and the pH of the waving lotion.
Impurities, volatile mercaptans and other by-products that are formed from complex reactions of the reducing or oxidizing agents with hair are also responsible for the post permanent malodor.
The profile, duration and intensity of the post-perm odor appears to be dependent on the concentration, reducing agent type used and pH of the waving lotion. Another factor in the post-perm odor is the odor intensity of the reducing agent. Waving lotions prepared with Cysteine and Bisulfite are less odoriferous than Ammonium Thioglycolate (ATG) and Glyceryl Thioglycolate (GTG)
There are no specific reaction mechanisms for the formation of the odoriferous residues in hair from the different type of reducing agents. However the post-perm odor in hair from the different reducing agents or perm products is easily differentiated by the human nose.
The present invention involves the reduction of post-permanent wave odors of hair permed with the Cysteamine reducing agent. Cysteamine is a beta-mercapto ethylamine compound having the chemical structure:HN2—CH2—CH2—SHThe pKSH is 8.27, and 77.15 molecular weight with a net positive charge.
Due to the molecular size and positive charge, Cysteamine has a high binding affinity to hair. This implies that diffusion rates of Cysteamine into and out of the hair are very different.
The post-permanent odor in hair permed with Cysteamine is very different than other reducing agents, including Ammonium Thioglycolate (ATG), Glyceryl Thioglycolate (GTG), Cysteine and Bisulfite. This post-perm malodor in hair is referred or described by individuals as “corn chips”, “burned pop corn” or “wet dog” or “cat urine”. The intensity of the post-perm malodor is also amplified by cigarette smokers and the body chemistry of individuals.
The malodor is not affected by shampooing and it persists in hair for many weeks. The malodor is not noticeable in dry hair but appears to be strong and is released upon water contact. The malodor is continuously being released upon rewetting of the hair. This water adsorption and desorption behavior of odoriferous cysteamine by-products suggest that they exhibit a high vapor pressure point in water and that they are trapped in the hair shaft or are an integral part of hair as residues of modified keratin.
These odoriferous compounds claimed in U.S. Pat. No. 5,554,363 are due to the formation of Thiazolidines, which are reaction products between cysteamine and aldehydic or carbonyl functional groups in hair as shown below.

The reaction between cysteamine and aldehyde or carbonyl functional groups occurs readily at pH 7.0-8.0, yielding stable five member ring Thiazolidine products. However, this reaction is very slow at pH less than 7.0 and very minimum at pH less than 4.0. The disclosure claims a pretreatment that reduces the post-perm hair odor by minimizing reactions of cysteamine with hair aldehyde sites or formation of the Thiazolidines with hair during the processing step. The pre-treatment includes carbonyl or aldehyde functional groups that will react with cysteamine producing non-odoriferous or pleasant smelling compounds in hair. However the effect of this pretreatment on hair mal-odor is very minimum and unsatisfactory.
Therefore, it is a principal object of the present invention to provide a hair treatment composition for reducing the odor in hair after a permanent wave operation which is long lasting and is easily applied to the hair after the permanent wave operation.
Another object of the present invention is to provide a hair treatment composition having the characteristic features described above which is retained in the hair fibers and avoids removal or dilution by normal hair shampooing or washing.
Another object of the present invention is to provide a hair treatment composition having the characteristic features described above which possesses a unique combination of fragrances that are retained by the hair fibers and effectively render any malodor to be more pleasant.
Another object of the present invention is to provide a hair treatment composition having the characteristic features described above which is capable of reducing, masking, and/or eliminating permanent wave malodor which occurs due to the re-wetting of hair fibers after a permanent wave operation.
Another object of the present invention is to provide a hair treatment composition having the characteristic features described above which also enhances the hair fibers by improving hair strength, shine, luster, and manageability.
Other and more specific objects will in part be obvious and will in part appear hereinafter.